Generally, a conventional yarn feeder has a winding wheel secured on a shaft, and an end of the shaft is pivotally connected to a frame while a body portion thereof is connected to a rim. Moreover, the rim is connected to a driving motor through a belt member such that the driving motor can drive the winding wheel to achieve the weaving processing. Moreover, in actual application, the weaving process needs a hundred of yarns weaved together at a time, and the yarns have to keep the same tension and extraction speed so as to produce high-quality weaving product.
However, the conventional yarn feeder is disadvantageous because: (i) the yarns are configured to be driven by a plurality of pulleys simultaneously, and the pulleys are further used for controlling the rotational speed of the yarns, which cannot precisely control tension and extraction speed of every yarn; and (ii) the driving motor can only indirectly drive the winding wheel through the belt member, and, for a period of time, the belt member is prone to be worn and have idling of transmission, which leads the imprecise in rotational speed control of the yarn feeder and in controlling the tension of yarn. Therefore, there remains a need for a new and improved design for a sensing apparatus for yarn feeder to overcome the problems presented above.